A device of this kind is known, for example, from German Patent Specification No. 873,908, but there are also numerous much older and also recent proposals. The following principle of operation is peculiar to them all:
The picture facing the viewing window is taken from the pile of pictures disposed in the housing by the transporter member, in the form of a hook which engages on an edge of the picture, through the upper slot between the housing and a so-called separator, which is the pile support means, since the hook is joined to the slider member. The separator holds back the rest of the pile of pictures. The picture then falls in the slider member to the bottom or is pressed to the bottom by auxiliary springs, and is forced by the slider member, during its return stroke or insertion stroke, through the lower picture slot under the separator, it being pushed between the pressure arrangement and the pile beneath the latter. The picture second from the top now lies against the viewing window for observation, and the operation can, if desired, be repeated.
These designs can be used when the picture thickness is adequate and when the pictures are precisely planar, but not for thin or deformed pictures from which the hook can slide, which not only interferes with the operation but also damages the picture surface and not last also that edge of the picture on which the hook must repeatedly engage. It is presumably for this reason that known devices of this type are not available on the market.
The object of the invention is to create a device of the type having a functionally reliable transporter member that does not damage the pictures.
It must be pointed out that rotatable transporter members in picture viewers are known per se. For example, German Patent Specification No. 864,759 discloses a stereo picture viewer fitted with rubber-coated rollers, in which the rollers are rotated by hand. Consequently it is not possible to change the picture quickly, so that disadvantageously long pauses occur between the individual pictures.
Furthermore, in this case at least two rollers are provided, one of which acts as a drive member while the other conveys the picture out of the viewing position back under the pile, and these rollers are coupled to one another by gear wheels.